Waste ferrous sulphate conversion into red ferric oxide pigments - of good quality, and into oxide(s) of sulphur, by calcination process

摘要

Red Fe2O3 pigments are mfd. from waste FeSO4.7H2O originating e.g. from TiO2 mfr. This ferrous sulphate, partially dehydrated and granulated, undergoes (1) calcination, with or without a reducing agent such as S being present; (2) washing; (3) pigmentary calcination at 750-1000 degrees C; (4) grinding. Fe2O3 pigments with orange-red to purplish-red tonality can be obtd., having an oil intake 12.5 pref. 10.5. Pigments with orange-red to red tonality can be obtd., which when incorporated in an oily base give a paint film with brilliancy >50. The pigments can have a resistivity >4000 ohm.cm. Process converts the waste ferrous sulphate into reusable or directly commercialisable prods. i.e. oxides of S which can be converted into H2SO4, and good quality red pigments.